38 MODEL AVIATION
Two slightly overpowered Cubs look to be having so much fun playing follow the
leader around the lake that the crowds go wild. It is definitely habit-forming.
As the O.S. .46-powered Lanier Mariner gets lower, its reflection gets closer. The pilot backs off the throttle, gradually adding more
elevator for another touch-and-go on the cool waters of Lake Red Bluff in California.
Take advantage of
some of the nicest
flying sites around
BEFORE THERE WERE airports in every
town, large expanses of water were some of
the best places to land an airplane. The first
floatplanes were built only a few years after
the Wright brothers had their successes with
flight in the late 1800s and early 1900s. Before
World War II, the largest and most advanced
airliners were seaplanes. Even today, many
full-scale aircraft are fitted with floats to take
advantage of the many harbors, rivers, and
lakes around the world.
I enjoy flying models from water because
it combines the fun of boating, flying, and a
day at the lake. It is hard to describe the thrill
of a smooth takeoff and landing on water. Of
all the people I know who have successfully
tried water flying, none have given it up. If
there is a float-fly near you, go check it out.
Float-flying events are usually
noncompetitive. They are typically laid-back
STATE
SPORT
o f t h e
by
Jim Feldmann
Flying From
the Water
July 2008 39
family occasions with many interesting
airplanes and great camaraderie among people
who share the same interests. And the flying is
fun to watch.
Most float-fliers love to do touch-and-gos,
so the action is right in front of you. You will
see all kinds of models, from park flyers to
trainers to multiengine scale masterpieces. The
skill levels represented will range from
beginner to pro.
Getting Started: If you find yourself totally
inspired, look at the seaplanes that are
available. The Sig Sealane kit and the Ace
Hobby Distributors Seamaster 40 ARF are two
of the most popular.
If you just want to get your feet wet (as it
were), the easiest way is to put floats on your
favorite land airplane. Great Planes and
Hangar 9 offer float sets with struts that can be
used on almost any 40- to 60-size model.
Other vendors such as Sea Commander Floats,
Hobby Lobby, and Plane Fun Floats offer
excellent floats and float kits in a variety of
sizes to fit everything from park flyers to Giant
Scale models.
You don’t need to wait for the next floatfly
event. All you need is an uncrowded body
of water, a floatplane, and some way to
retrieve your model. You can’t always get the
airplane back to shore; unless you’re an
This Great Planes Super Stearman is
modified with a ventral fin to
compensate for the floats’ added side
area. It flew well on a piped gasoline
engine. Biplanes look so good on floats.
Isn’t that pretty? The giant-scale clipped-wing Cub on floats flies scalelike and hovers inches
off the surface. If you are really good, you can dip the rudder into the water. This pilot did!
Photos by Michael Brown
Olympic swimmer, you will need a boat, kayak, canoe, or something to
get out to the model and back.
Of course you should not fly where it is prohibited or where you
might endanger other people or property. For safety, wear a life vest in
that recovery boat and be sure to have someone with you in case of an
emergency.
The ideal water flying site will have a smooth beach or a dock where
you can launch and recover the aircraft, unobstructed overflight areas,
water that is smooth or with up to roughly a 2-inch chop, wind parallel
to the shoreline, and the sun behind you. Look around your area; you
may find that the local RC club already has a float-flying site chosen.
Making a Good Float Setup: Attaching and setting up floats is not
difficult, although you may need to modify the float mounting struts that
come with the set or make your own to fit your particular airplane. There
have been numerous technical articles describing it all in great detail.
The details are often conflicting, but don’t worry; you can be quite
far from the ideals without having serious problems. Following are the
accepted rules of thumb.
• The floats should be approximately 75% of the fuselage’s length from
the propeller to the rudder hinge line.
• The distance between the floats should be roughly 25% of the
wingspan.
• The float step should be directly under the airplane’s recommended
CG, plus or minus 1/2 inch or so.
• The top of the float should be at least 2 inches below the bottom of the
propeller arc.
• The top of the float should be positioned 0°-2° negative to the
horizontal stabilizer.
• There should be a spreader bar front and rear between the floats to
keep them parallel to each other at all times.
• If the combined area of your model’s vertical fin plus the part of the
rudder above the horizontal stabilizer is less than 8% of the wing area,
add a ventral fin to bring the total area up to 8%-10%.
The Laddie Mikulasko-designed Northstar
as an amphibian. Available as a kit from
Balsa USA, it handles great with a .46 twostroke
and is super-groovy in the air. It is
unlikely that this model will flip in a
crosswind.
40 MODEL AVIATION
Sam Arrigo’s (Grants Pass OR) Seamaster
was built from a kit and covered in an
outstanding high-visibility color scheme.
Seaplanes are another way to fly from
water, and they perform the same as lightly
loaded sport models.
This O.S. .91-powered World Models
Super Sports Senior on 120-size floats is
smooth, stable, and easy to fly with or
without floats. Lightly loaded, low-wing
sport models make some of the nicestflying
floatplanes.
The Herr Aqua Star is a three-channel, 1/2A
design that can fly around in small ponds
and light winds. Modifying it for electric
power is a snap.
A Midwest Aero-Star on Slocan floats
taxis back from a flight. Don’t let the
overcast skies stop you from flying; floats
make a model more stable and easier to
see in the air.
A typical float-fly flightline. Some have big crowds and some have
only a few club members and friends. Big crowds mean more
diversity, and small groups mean more flight time. Both are great!
Airplanes such as this Pacific Aeromodel Lazy Days three-channel
electric on GWS floats flies so slowly and gently that we often refer
to them as “lawn-chair fliers.” They are limited to no-wind
conditions, though.
Scale floatplanes such as Hangar 9’s Cessna can fly well; they
don’t have to be Cubs. The heavier they are, the longer the
takeoff run they’ll need.
July 2008 41
Water-Proofing
Your Investment
In normal use on
water, you need to
protect your model and
equipment against spray
and splashes. Water will
try to get under the
covering and lift it. It can
also cause mildew to grow
inside the airframe.
A few drops of water
inside the fuselage are not
a flight problem. However, as it runs back and forth, a lot of it can
cause the CG to move. In the worst case it could stop the radio
from working. Low-wing airplanes are better in this regard, because
any water that gets into the fuselage will tend to run back out
through the wing saddle.
Make sure the radio equipment is not mounted on the fuselage
floor; that’s where water accumulates. Go over the airplane and
seal all exposed wood with thin cyanoacrylate or epoxy. Make it
part of your regular preflight routine to examine the covering and
iron down any loose seams.
Use silicone sealant to close any openings around externally
mounted servos. If you have hatch-mounted servos with a large
slot for the arm, make a small shield for the slots from covered
balsa or the clear blister packs that hardware comes in. (Small
bubble canopies are a great resource.) Seal any openings between
the engine compartment and the fuselage.
Most servos today are quite water-resistant and tube-in-a-tube
pushrods seldom leak water into the fuselage, so you don’t need to
worry too much about them. The best way to seal the wing saddle
is with foam wing-saddle tape. Make sure the front and back as well
as both sides are sealed.
Hollow floats like to leak. Make it a practice to tip the airplane
nose down and then tail down to listen for water running back and
forth inside the floats. MA
—Jim Feldmann
A high-end version of the model-rescue boat! Bob Harts has
donated its use and himself all 17 years the local float-fly has
been taking place.
As does RC flying in general, float-flying appeals to all ages. Jim
Finch, who owns hobby shops in Redding and Eureka CA, helps
Logan Shaw, who ended his first float flight smiling.
Some sort of retrieval boat is required. Organized float-flys often
have sophisticated arrangements, but a canoe, a kayak such as the
one Charlie Hoisington (Redding CA) is using, or a two-man
inflatable will work as well.
Twin-rotor autogyro on floats, anyone? These models are
becoming extremely popular at indoor events. This one is built
from the GWS Slow Stick and equipped with GWS floats.
It is often said, “If it will fly on wheels, it will
fly on floats.” Richard Lucas (Fort Bragg
CA) learned that his rotating-wing (not
rotary wing) model flies either way.
E-flite’s Mini Ultra Stick is a terrific compact
electric aerobat, and it is just as good on
floats. You can throw it in your car’s trunk
and fly it almost anywhere there is water.
Some of the earliest full-scale airplanes were
sometimes put on floats. Balsa USA’s Taube
sports a set of tail-dragger floats, which take
some getting used to.
This is one of the safest recovery methods.
He doesn’t even have to lean over to pick
up the airplane. There is often as much
ingenuity in retrieval methods as there is
in the models themselves.
Scale seaplanes such as Great Planes’ Seawind can be a
handful on the water. Jim Feldmann made this pictureperfect
takeoff. He really enjoys this model.
The quickest way to start float-flying is to put floats on an old trainer you don’t
use much anymore. This Avistar flies as well on sheeted-foam floats as it did on
wheels. Keep the weight down with light floats and struts, and the model won’t
know they’re there.
42 MODEL AVIATION
Bruce Taylor and Nick Troehler share the duty of
bringing in a stalled Seamaster. Rule number one at a
float-fly: Don’t strafe the retrieval boat!
What Models Work Best?
Almost any airplane (or helicopter) will work on floats, but some
do better than others. Floats add a fair amount of weight to a model,
so you should start with a model that has a low wing loading, such as
a trainer or a light sport aircraft.
A low-wing airplane will work better on water than a high-wing
airplane will, simply because the wing is closer to the water and less
likely to be blown over in a crosswind taxi. Low-wingers are better
balanced for aerobatics too, with the floats below the wing and the
rest of the airplane above it.
High-wingers on floats are exceptionally stable in the air.
However, the extreme pendulum effect of the floats hanging down
under the fuselage makes turns and rolling maneuvers look strange.
Scale models tend to be harder to fly than sport models, and scale
floatplanes (such as the ubiquitous
Cub) are harder to fly than sport
floatplanes. The best-performing
and easiest-to-fly floatplane would
be something similar to a Sig Four-
Star kit or ARF, Goldberg Tiger kit
or ARF, or any of the Stick
variations. MA
—Jim Feldmann
• Set your airplane’s rudder for all the travel
you can get, and use exponential as needed to
calm it around center.
• Water rudders are optional. High-wing and
multiengine models usually need them; lowwing
models usually don’t.
• Rebalance the airplane after the floats (and
ventral fin, if used) are installed. If you need to
add balance weight, add it to the floats—not
the airplane.
Propellers: Wood propellers don’t mix with
water. The water that splashes into the
propeller will shred the wood before you even
get off the water. You can use any plastic
propellers, such as those from APC or Master
Airscrew.
The wind has a much greater effect on the
model when it’s taxiing on water than on land;
the water gives, where the ground stays put.
No matter which way the airplane is pointed, it
will move downwind unless you drive it some
other way. If there is a current in the water,
that will also have an effect. Taxiing on water
is similar to taxiing a tail-dragger on land.
When taxiing in a straight line, hold full
up-elevator and use approximately one-third
throttle to keep the back of the floats down in
the water and give the air rudder plenty of
steering authority.
If the floats come up on the step, slow
down until they settle back into the water. A
fast taxi on the step is a good technique for
windy conditions, but it requires practice. You
better take it slow.
When turning, slow to a walking pace,
release the elevator, and steer with the air
rudder, using bursts of throttle to kick the tail
around as needed. Hold full aileron toward the
wind to keep the upwind wing down.
Taking off From Water: Doing this is similar
to taking off from land with a tail-dragger. It is
actually easier to take off from water because
you can normally take off directly into the
wind, and you will need much less right
rudder to counteract torque.
Taxi out to the takeoff area, throttle back,
and let the airplane weather-vane into the
wind; you should still be holding full upelevator.
Advance the throttle smoothly while
releasing the elevator. The airplane will rise up
on top of the water and run along like a fast
boat.
When the airplane has reached flying
speed, add slight up-elevator and the airplane
will break the surface tension of the water and
take off. That “break” may cause a radical
pitch-up attitude, which you should quickly
correct to prevent a stall. Remember that
flying speed will need to be a bit faster
because of the floats’ weight.
Hold slight up-elevator until your model is
well out of ground effect. If you have a water
rudder, do not move the rudder stick during
the high-speed takeoff run. Water rudders are
incredibly effective at high speeds and can
easily cause a water loop.
Flying a Floatplane: Your model will fly
almost the same on floats as it did on wheels.
You will need a little up-trim on the elevator
to counteract the floats’ drag. The airplane is
heavier and draggier than it was on wheels, so
it will climb slower and come down faster.
Floats have a tendency to tame aircraft, so
you’ll find that aerobatics will be bigger and
smoother. The floats will create added lift and
actually make inverted and knife-edge
maneuvers easier. Be cautious when
performing spins; the added momentum of the
floats can make it more difficult to recover.
Landing a Floatplane on Water: Again, the
floatplane acts like a tail-dragger on land. All
water landings should be flared three-point
touchdowns. There is a great deal of drag
when the floats touch the water, and if you fly
the model onto the water in a wheel-landing
(tail high) attitude, there is a good chance that
it will flip upside down.
Following are some landing rules.
• Land directly into the wind, and try to land
downwind of your retrieval point.
• Keep your floatplane’s speed slightly faster
than you would for a ground landing.
• Fly down to a couple feet above the water
and then cut the throttle and flare by holding
altitude with the elevator. As the speed bleeds
off, the airplane will slowly settle onto the
water. Once on the water, the airplane will
slow more quickly than it does on land.
• Taxi back to shore in as straight a line as
possible to avoid taxiing crosswind. Keep that
upwind wing down by holding the aileron up.
• Try to wipe that silly grin off your face!
Everything is going to get wet if you flip
your model over or crash it. Fresh water will
not permanently damage your engine or radio
if you dry them out as soon as you get them
out of the water. Salt water, on the other hand,
will quickly destroy them.
If the worst happens, start the engine and
run it until it is good and hot, to evaporate any
water that is inside. Run it for at least five
minutes for a two-stroke and a whole tank of
fuel for a four-stroke. Then load up the engine
with a liberal dose of after-run oil.
Take the receiver, battery, switch, and any
servos that were underwater out of the
airplane and open them up. Blow out as much
water as you can, and then let them dry in the
sun.
Damage to electronics occurs when
mineral deposits form on metals. Lake water
is loaded with minerals. Using a soft plastic
brush and distilled water will help clean
electronics that might be dirty.
Both the engine and the radio should be
fine after the water has completely
evaporated. The model will typically survive
and can be repaired once the parts are dry.
Tips for Success: There are several things
you should pay attention to if you want your
first float-flying experience to be successful.
Avoid flying an underpowered model; you
will need a little more power for takeoffs from
water. This is not a problem for the average
sport model, but a low-powered trainer or
scale airplane might need more. Switching to
a larger-diameter, lower-pitch propeller may
help.
The rules of thumb regarding an improper
float setup are flexible, but there are limits.
Floats that are mounted too close together, not
parallel to each other or to the fuselage, or
with the step too far forward or too far back
will be problematic. The step should be under
or ahead of the CG.
Too much or not enough positive incidence
in the wing will make it difficult or impossible
for the model to take off from water.
Not having enough area in the fin and
rudder to offset the float area added in front of
the CG, which frequently happens with the J-3
Cub, will make the airplane unstable at takeoff
or during slow flight. If you don’t want to do
the math, add a subfin just to be safe.
If the airspeed on takeoff or landing is too
slow, the model will stall. Remember that you
need more speed to lift the extra weight of the
floats. If your airplane takes off too soon or
slows too much on the landing approach, it
will stall and everything will get wet. The full
throttle-and-full up method of takeoff seldom
works on the water.
Examine the float design carefully. The
shape and finish of the bottom of the floats is
critical. It is probably best to buy your first set
of floats. If you want to build them from
scratch, wait until after you know more about
them.
Flying from water is another great way to
enjoy model aircraft, and it is so much fun that
it is almost addictive. Try it; I bet you’ll like
it! MA
Jim Feldmann
[email protected]
Sources:
Ace Hobby Distributors
(949) 900-3300
www.acehobby.com
APC Propellers
(530) 661-0399
www.apcprop.com
Carl Goldberg Products
(217) 398-8970
www.carlgoldbergmodels.com
Great Planes Model Distributors
(217) 398-8970
www.greatplanes.com
Hangar 9
(800) 338-4639
www.hangar-9.com
Hobby Lobby International
(866) 933-5972
www.hobby-lobby.com
Master Airscrew
www.masterairscrew.com
Plane Fun Floats
www.geocities.com/planefunfloats
Sea Commander
(604) 485-2976
www.seacommander.com
Sig Manufacturing
(641) 623-5154
www.sigmfg.com
July 2008 43
Edition: Model Aviation - 2008/07
Page Numbers: 38,39,40,41,42,43
Edition: Model Aviation - 2008/07
Page Numbers: 38,39,40,41,42,43
38 MODEL AVIATION
Two slightly overpowered Cubs look to be having so much fun playing follow the
leader around the lake that the crowds go wild. It is definitely habit-forming.
As the O.S. .46-powered Lanier Mariner gets lower, its reflection gets closer. The pilot backs off the throttle, gradually adding more
elevator for another touch-and-go on the cool waters of Lake Red Bluff in California.
Take advantage of
some of the nicest
flying sites around
BEFORE THERE WERE airports in every
town, large expanses of water were some of
the best places to land an airplane. The first
floatplanes were built only a few years after
the Wright brothers had their successes with
flight in the late 1800s and early 1900s. Before
World War II, the largest and most advanced
airliners were seaplanes. Even today, many
full-scale aircraft are fitted with floats to take
advantage of the many harbors, rivers, and
lakes around the world.
I enjoy flying models from water because
it combines the fun of boating, flying, and a
day at the lake. It is hard to describe the thrill
of a smooth takeoff and landing on water. Of
all the people I know who have successfully
tried water flying, none have given it up. If
there is a float-fly near you, go check it out.
Float-flying events are usually
noncompetitive. They are typically laid-back
STATE
SPORT
o f t h e
by
Jim Feldmann
Flying From
the Water
July 2008 39
family occasions with many interesting
airplanes and great camaraderie among people
who share the same interests. And the flying is
fun to watch.
Most float-fliers love to do touch-and-gos,
so the action is right in front of you. You will
see all kinds of models, from park flyers to
trainers to multiengine scale masterpieces. The
skill levels represented will range from
beginner to pro.
Getting Started: If you find yourself totally
inspired, look at the seaplanes that are
available. The Sig Sealane kit and the Ace
Hobby Distributors Seamaster 40 ARF are two
of the most popular.
If you just want to get your feet wet (as it
were), the easiest way is to put floats on your
favorite land airplane. Great Planes and
Hangar 9 offer float sets with struts that can be
used on almost any 40- to 60-size model.
Other vendors such as Sea Commander Floats,
Hobby Lobby, and Plane Fun Floats offer
excellent floats and float kits in a variety of
sizes to fit everything from park flyers to Giant
Scale models.
You don’t need to wait for the next floatfly
event. All you need is an uncrowded body
of water, a floatplane, and some way to
retrieve your model. You can’t always get the
airplane back to shore; unless you’re an
This Great Planes Super Stearman is
modified with a ventral fin to
compensate for the floats’ added side
area. It flew well on a piped gasoline
engine. Biplanes look so good on floats.
Isn’t that pretty? The giant-scale clipped-wing Cub on floats flies scalelike and hovers inches
off the surface. If you are really good, you can dip the rudder into the water. This pilot did!
Photos by Michael Brown
Olympic swimmer, you will need a boat, kayak, canoe, or something to
get out to the model and back.
Of course you should not fly where it is prohibited or where you
might endanger other people or property. For safety, wear a life vest in
that recovery boat and be sure to have someone with you in case of an
emergency.
The ideal water flying site will have a smooth beach or a dock where
you can launch and recover the aircraft, unobstructed overflight areas,
water that is smooth or with up to roughly a 2-inch chop, wind parallel
to the shoreline, and the sun behind you. Look around your area; you
may find that the local RC club already has a float-flying site chosen.
Making a Good Float Setup: Attaching and setting up floats is not
difficult, although you may need to modify the float mounting struts that
come with the set or make your own to fit your particular airplane. There
have been numerous technical articles describing it all in great detail.
The details are often conflicting, but don’t worry; you can be quite
far from the ideals without having serious problems. Following are the
accepted rules of thumb.
• The floats should be approximately 75% of the fuselage’s length from
the propeller to the rudder hinge line.
• The distance between the floats should be roughly 25% of the
wingspan.
• The float step should be directly under the airplane’s recommended
CG, plus or minus 1/2 inch or so.
• The top of the float should be at least 2 inches below the bottom of the
propeller arc.
• The top of the float should be positioned 0°-2° negative to the
horizontal stabilizer.
• There should be a spreader bar front and rear between the floats to
keep them parallel to each other at all times.
• If the combined area of your model’s vertical fin plus the part of the
rudder above the horizontal stabilizer is less than 8% of the wing area,
add a ventral fin to bring the total area up to 8%-10%.
The Laddie Mikulasko-designed Northstar
as an amphibian. Available as a kit from
Balsa USA, it handles great with a .46 twostroke
and is super-groovy in the air. It is
unlikely that this model will flip in a
crosswind.
40 MODEL AVIATION
Sam Arrigo’s (Grants Pass OR) Seamaster
was built from a kit and covered in an
outstanding high-visibility color scheme.
Seaplanes are another way to fly from
water, and they perform the same as lightly
loaded sport models.
This O.S. .91-powered World Models
Super Sports Senior on 120-size floats is
smooth, stable, and easy to fly with or
without floats. Lightly loaded, low-wing
sport models make some of the nicestflying
floatplanes.
The Herr Aqua Star is a three-channel, 1/2A
design that can fly around in small ponds
and light winds. Modifying it for electric
power is a snap.
A Midwest Aero-Star on Slocan floats
taxis back from a flight. Don’t let the
overcast skies stop you from flying; floats
make a model more stable and easier to
see in the air.
A typical float-fly flightline. Some have big crowds and some have
only a few club members and friends. Big crowds mean more
diversity, and small groups mean more flight time. Both are great!
Airplanes such as this Pacific Aeromodel Lazy Days three-channel
electric on GWS floats flies so slowly and gently that we often refer
to them as “lawn-chair fliers.” They are limited to no-wind
conditions, though.
Scale floatplanes such as Hangar 9’s Cessna can fly well; they
don’t have to be Cubs. The heavier they are, the longer the
takeoff run they’ll need.
July 2008 41
Water-Proofing
Your Investment
In normal use on
water, you need to
protect your model and
equipment against spray
and splashes. Water will
try to get under the
covering and lift it. It can
also cause mildew to grow
inside the airframe.
A few drops of water
inside the fuselage are not
a flight problem. However, as it runs back and forth, a lot of it can
cause the CG to move. In the worst case it could stop the radio
from working. Low-wing airplanes are better in this regard, because
any water that gets into the fuselage will tend to run back out
through the wing saddle.
Make sure the radio equipment is not mounted on the fuselage
floor; that’s where water accumulates. Go over the airplane and
seal all exposed wood with thin cyanoacrylate or epoxy. Make it
part of your regular preflight routine to examine the covering and
iron down any loose seams.
Use silicone sealant to close any openings around externally
mounted servos. If you have hatch-mounted servos with a large
slot for the arm, make a small shield for the slots from covered
balsa or the clear blister packs that hardware comes in. (Small
bubble canopies are a great resource.) Seal any openings between
the engine compartment and the fuselage.
Most servos today are quite water-resistant and tube-in-a-tube
pushrods seldom leak water into the fuselage, so you don’t need to
worry too much about them. The best way to seal the wing saddle
is with foam wing-saddle tape. Make sure the front and back as well
as both sides are sealed.
Hollow floats like to leak. Make it a practice to tip the airplane
nose down and then tail down to listen for water running back and
forth inside the floats. MA
—Jim Feldmann
A high-end version of the model-rescue boat! Bob Harts has
donated its use and himself all 17 years the local float-fly has
been taking place.
As does RC flying in general, float-flying appeals to all ages. Jim
Finch, who owns hobby shops in Redding and Eureka CA, helps
Logan Shaw, who ended his first float flight smiling.
Some sort of retrieval boat is required. Organized float-flys often
have sophisticated arrangements, but a canoe, a kayak such as the
one Charlie Hoisington (Redding CA) is using, or a two-man
inflatable will work as well.
Twin-rotor autogyro on floats, anyone? These models are
becoming extremely popular at indoor events. This one is built
from the GWS Slow Stick and equipped with GWS floats.
It is often said, “If it will fly on wheels, it will
fly on floats.” Richard Lucas (Fort Bragg
CA) learned that his rotating-wing (not
rotary wing) model flies either way.
E-flite’s Mini Ultra Stick is a terrific compact
electric aerobat, and it is just as good on
floats. You can throw it in your car’s trunk
and fly it almost anywhere there is water.
Some of the earliest full-scale airplanes were
sometimes put on floats. Balsa USA’s Taube
sports a set of tail-dragger floats, which take
some getting used to.
This is one of the safest recovery methods.
He doesn’t even have to lean over to pick
up the airplane. There is often as much
ingenuity in retrieval methods as there is
in the models themselves.
Scale seaplanes such as Great Planes’ Seawind can be a
handful on the water. Jim Feldmann made this pictureperfect
takeoff. He really enjoys this model.
The quickest way to start float-flying is to put floats on an old trainer you don’t
use much anymore. This Avistar flies as well on sheeted-foam floats as it did on
wheels. Keep the weight down with light floats and struts, and the model won’t
know they’re there.
42 MODEL AVIATION
Bruce Taylor and Nick Troehler share the duty of
bringing in a stalled Seamaster. Rule number one at a
float-fly: Don’t strafe the retrieval boat!
What Models Work Best?
Almost any airplane (or helicopter) will work on floats, but some
do better than others. Floats add a fair amount of weight to a model,
so you should start with a model that has a low wing loading, such as
a trainer or a light sport aircraft.
A low-wing airplane will work better on water than a high-wing
airplane will, simply because the wing is closer to the water and less
likely to be blown over in a crosswind taxi. Low-wingers are better
balanced for aerobatics too, with the floats below the wing and the
rest of the airplane above it.
High-wingers on floats are exceptionally stable in the air.
However, the extreme pendulum effect of the floats hanging down
under the fuselage makes turns and rolling maneuvers look strange.
Scale models tend to be harder to fly than sport models, and scale
floatplanes (such as the ubiquitous
Cub) are harder to fly than sport
floatplanes. The best-performing
and easiest-to-fly floatplane would
be something similar to a Sig Four-
Star kit or ARF, Goldberg Tiger kit
or ARF, or any of the Stick
variations. MA
—Jim Feldmann
• Set your airplane’s rudder for all the travel
you can get, and use exponential as needed to
calm it around center.
• Water rudders are optional. High-wing and
multiengine models usually need them; lowwing
models usually don’t.
• Rebalance the airplane after the floats (and
ventral fin, if used) are installed. If you need to
add balance weight, add it to the floats—not
the airplane.
Propellers: Wood propellers don’t mix with
water. The water that splashes into the
propeller will shred the wood before you even
get off the water. You can use any plastic
propellers, such as those from APC or Master
Airscrew.
The wind has a much greater effect on the
model when it’s taxiing on water than on land;
the water gives, where the ground stays put.
No matter which way the airplane is pointed, it
will move downwind unless you drive it some
other way. If there is a current in the water,
that will also have an effect. Taxiing on water
is similar to taxiing a tail-dragger on land.
When taxiing in a straight line, hold full
up-elevator and use approximately one-third
throttle to keep the back of the floats down in
the water and give the air rudder plenty of
steering authority.
If the floats come up on the step, slow
down until they settle back into the water. A
fast taxi on the step is a good technique for
windy conditions, but it requires practice. You
better take it slow.
When turning, slow to a walking pace,
release the elevator, and steer with the air
rudder, using bursts of throttle to kick the tail
around as needed. Hold full aileron toward the
wind to keep the upwind wing down.
Taking off From Water: Doing this is similar
to taking off from land with a tail-dragger. It is
actually easier to take off from water because
you can normally take off directly into the
wind, and you will need much less right
rudder to counteract torque.
Taxi out to the takeoff area, throttle back,
and let the airplane weather-vane into the
wind; you should still be holding full upelevator.
Advance the throttle smoothly while
releasing the elevator. The airplane will rise up
on top of the water and run along like a fast
boat.
When the airplane has reached flying
speed, add slight up-elevator and the airplane
will break the surface tension of the water and
take off. That “break” may cause a radical
pitch-up attitude, which you should quickly
correct to prevent a stall. Remember that
flying speed will need to be a bit faster
because of the floats’ weight.
Hold slight up-elevator until your model is
well out of ground effect. If you have a water
rudder, do not move the rudder stick during
the high-speed takeoff run. Water rudders are
incredibly effective at high speeds and can
easily cause a water loop.
Flying a Floatplane: Your model will fly
almost the same on floats as it did on wheels.
You will need a little up-trim on the elevator
to counteract the floats’ drag. The airplane is
heavier and draggier than it was on wheels, so
it will climb slower and come down faster.
Floats have a tendency to tame aircraft, so
you’ll find that aerobatics will be bigger and
smoother. The floats will create added lift and
actually make inverted and knife-edge
maneuvers easier. Be cautious when
performing spins; the added momentum of the
floats can make it more difficult to recover.
Landing a Floatplane on Water: Again, the
floatplane acts like a tail-dragger on land. All
water landings should be flared three-point
touchdowns. There is a great deal of drag
when the floats touch the water, and if you fly
the model onto the water in a wheel-landing
(tail high) attitude, there is a good chance that
it will flip upside down.
Following are some landing rules.
• Land directly into the wind, and try to land
downwind of your retrieval point.
• Keep your floatplane’s speed slightly faster
than you would for a ground landing.
• Fly down to a couple feet above the water
and then cut the throttle and flare by holding
altitude with the elevator. As the speed bleeds
off, the airplane will slowly settle onto the
water. Once on the water, the airplane will
slow more quickly than it does on land.
• Taxi back to shore in as straight a line as
possible to avoid taxiing crosswind. Keep that
upwind wing down by holding the aileron up.
• Try to wipe that silly grin off your face!
Everything is going to get wet if you flip
your model over or crash it. Fresh water will
not permanently damage your engine or radio
if you dry them out as soon as you get them
out of the water. Salt water, on the other hand,
will quickly destroy them.
If the worst happens, start the engine and
run it until it is good and hot, to evaporate any
water that is inside. Run it for at least five
minutes for a two-stroke and a whole tank of
fuel for a four-stroke. Then load up the engine
with a liberal dose of after-run oil.
Take the receiver, battery, switch, and any
servos that were underwater out of the
airplane and open them up. Blow out as much
water as you can, and then let them dry in the
sun.
Damage to electronics occurs when
mineral deposits form on metals. Lake water
is loaded with minerals. Using a soft plastic
brush and distilled water will help clean
electronics that might be dirty.
Both the engine and the radio should be
fine after the water has completely
evaporated. The model will typically survive
and can be repaired once the parts are dry.
Tips for Success: There are several things
you should pay attention to if you want your
first float-flying experience to be successful.
Avoid flying an underpowered model; you
will need a little more power for takeoffs from
water. This is not a problem for the average
sport model, but a low-powered trainer or
scale airplane might need more. Switching to
a larger-diameter, lower-pitch propeller may
help.
The rules of thumb regarding an improper
float setup are flexible, but there are limits.
Floats that are mounted too close together, not
parallel to each other or to the fuselage, or
with the step too far forward or too far back
will be problematic. The step should be under
or ahead of the CG.
Too much or not enough positive incidence
in the wing will make it difficult or impossible
for the model to take off from water.
Not having enough area in the fin and
rudder to offset the float area added in front of
the CG, which frequently happens with the J-3
Cub, will make the airplane unstable at takeoff
or during slow flight. If you don’t want to do
the math, add a subfin just to be safe.
If the airspeed on takeoff or landing is too
slow, the model will stall. Remember that you
need more speed to lift the extra weight of the
floats. If your airplane takes off too soon or
slows too much on the landing approach, it
will stall and everything will get wet. The full
throttle-and-full up method of takeoff seldom
works on the water.
Examine the float design carefully. The
shape and finish of the bottom of the floats is
critical. It is probably best to buy your first set
of floats. If you want to build them from
scratch, wait until after you know more about
them.
Flying from water is another great way to
enjoy model aircraft, and it is so much fun that
it is almost addictive. Try it; I bet you’ll like
it! MA
Jim Feldmann
[email protected]
Sources:
Ace Hobby Distributors
(949) 900-3300
www.acehobby.com
APC Propellers
(530) 661-0399
www.apcprop.com
Carl Goldberg Products
(217) 398-8970
www.carlgoldbergmodels.com
Great Planes Model Distributors
(217) 398-8970
www.greatplanes.com
Hangar 9
(800) 338-4639
www.hangar-9.com
Hobby Lobby International
(866) 933-5972
www.hobby-lobby.com
Master Airscrew
www.masterairscrew.com
Plane Fun Floats
www.geocities.com/planefunfloats
Sea Commander
(604) 485-2976
www.seacommander.com
Sig Manufacturing
(641) 623-5154
www.sigmfg.com
July 2008 43
Edition: Model Aviation - 2008/07
Page Numbers: 38,39,40,41,42,43
38 MODEL AVIATION
Two slightly overpowered Cubs look to be having so much fun playing follow the
leader around the lake that the crowds go wild. It is definitely habit-forming.
As the O.S. .46-powered Lanier Mariner gets lower, its reflection gets closer. The pilot backs off the throttle, gradually adding more
elevator for another touch-and-go on the cool waters of Lake Red Bluff in California.
Take advantage of
some of the nicest
flying sites around
BEFORE THERE WERE airports in every
town, large expanses of water were some of
the best places to land an airplane. The first
floatplanes were built only a few years after
the Wright brothers had their successes with
flight in the late 1800s and early 1900s. Before
World War II, the largest and most advanced
airliners were seaplanes. Even today, many
full-scale aircraft are fitted with floats to take
advantage of the many harbors, rivers, and
lakes around the world.
I enjoy flying models from water because
it combines the fun of boating, flying, and a
day at the lake. It is hard to describe the thrill
of a smooth takeoff and landing on water. Of
all the people I know who have successfully
tried water flying, none have given it up. If
there is a float-fly near you, go check it out.
Float-flying events are usually
noncompetitive. They are typically laid-back
STATE
SPORT
o f t h e
by
Jim Feldmann
Flying From
the Water
July 2008 39
family occasions with many interesting
airplanes and great camaraderie among people
who share the same interests. And the flying is
fun to watch.
Most float-fliers love to do touch-and-gos,
so the action is right in front of you. You will
see all kinds of models, from park flyers to
trainers to multiengine scale masterpieces. The
skill levels represented will range from
beginner to pro.
Getting Started: If you find yourself totally
inspired, look at the seaplanes that are
available. The Sig Sealane kit and the Ace
Hobby Distributors Seamaster 40 ARF are two
of the most popular.
If you just want to get your feet wet (as it
were), the easiest way is to put floats on your
favorite land airplane. Great Planes and
Hangar 9 offer float sets with struts that can be
used on almost any 40- to 60-size model.
Other vendors such as Sea Commander Floats,
Hobby Lobby, and Plane Fun Floats offer
excellent floats and float kits in a variety of
sizes to fit everything from park flyers to Giant
Scale models.
You don’t need to wait for the next floatfly
event. All you need is an uncrowded body
of water, a floatplane, and some way to
retrieve your model. You can’t always get the
airplane back to shore; unless you’re an
This Great Planes Super Stearman is
modified with a ventral fin to
compensate for the floats’ added side
area. It flew well on a piped gasoline
engine. Biplanes look so good on floats.
Isn’t that pretty? The giant-scale clipped-wing Cub on floats flies scalelike and hovers inches
off the surface. If you are really good, you can dip the rudder into the water. This pilot did!
Photos by Michael Brown
Olympic swimmer, you will need a boat, kayak, canoe, or something to
get out to the model and back.
Of course you should not fly where it is prohibited or where you
might endanger other people or property. For safety, wear a life vest in
that recovery boat and be sure to have someone with you in case of an
emergency.
The ideal water flying site will have a smooth beach or a dock where
you can launch and recover the aircraft, unobstructed overflight areas,
water that is smooth or with up to roughly a 2-inch chop, wind parallel
to the shoreline, and the sun behind you. Look around your area; you
may find that the local RC club already has a float-flying site chosen.
Making a Good Float Setup: Attaching and setting up floats is not
difficult, although you may need to modify the float mounting struts that
come with the set or make your own to fit your particular airplane. There
have been numerous technical articles describing it all in great detail.
The details are often conflicting, but don’t worry; you can be quite
far from the ideals without having serious problems. Following are the
accepted rules of thumb.
• The floats should be approximately 75% of the fuselage’s length from
the propeller to the rudder hinge line.
• The distance between the floats should be roughly 25% of the
wingspan.
• The float step should be directly under the airplane’s recommended
CG, plus or minus 1/2 inch or so.
• The top of the float should be at least 2 inches below the bottom of the
propeller arc.
• The top of the float should be positioned 0°-2° negative to the
horizontal stabilizer.
• There should be a spreader bar front and rear between the floats to
keep them parallel to each other at all times.
• If the combined area of your model’s vertical fin plus the part of the
rudder above the horizontal stabilizer is less than 8% of the wing area,
add a ventral fin to bring the total area up to 8%-10%.
The Laddie Mikulasko-designed Northstar
as an amphibian. Available as a kit from
Balsa USA, it handles great with a .46 twostroke
and is super-groovy in the air. It is
unlikely that this model will flip in a
crosswind.
40 MODEL AVIATION
Sam Arrigo’s (Grants Pass OR) Seamaster
was built from a kit and covered in an
outstanding high-visibility color scheme.
Seaplanes are another way to fly from
water, and they perform the same as lightly
loaded sport models.
This O.S. .91-powered World Models
Super Sports Senior on 120-size floats is
smooth, stable, and easy to fly with or
without floats. Lightly loaded, low-wing
sport models make some of the nicestflying
floatplanes.
The Herr Aqua Star is a three-channel, 1/2A
design that can fly around in small ponds
and light winds. Modifying it for electric
power is a snap.
A Midwest Aero-Star on Slocan floats
taxis back from a flight. Don’t let the
overcast skies stop you from flying; floats
make a model more stable and easier to
see in the air.
A typical float-fly flightline. Some have big crowds and some have
only a few club members and friends. Big crowds mean more
diversity, and small groups mean more flight time. Both are great!
Airplanes such as this Pacific Aeromodel Lazy Days three-channel
electric on GWS floats flies so slowly and gently that we often refer
to them as “lawn-chair fliers.” They are limited to no-wind
conditions, though.
Scale floatplanes such as Hangar 9’s Cessna can fly well; they
don’t have to be Cubs. The heavier they are, the longer the
takeoff run they’ll need.
July 2008 41
Water-Proofing
Your Investment
In normal use on
water, you need to
protect your model and
equipment against spray
and splashes. Water will
try to get under the
covering and lift it. It can
also cause mildew to grow
inside the airframe.
A few drops of water
inside the fuselage are not
a flight problem. However, as it runs back and forth, a lot of it can
cause the CG to move. In the worst case it could stop the radio
from working. Low-wing airplanes are better in this regard, because
any water that gets into the fuselage will tend to run back out
through the wing saddle.
Make sure the radio equipment is not mounted on the fuselage
floor; that’s where water accumulates. Go over the airplane and
seal all exposed wood with thin cyanoacrylate or epoxy. Make it
part of your regular preflight routine to examine the covering and
iron down any loose seams.
Use silicone sealant to close any openings around externally
mounted servos. If you have hatch-mounted servos with a large
slot for the arm, make a small shield for the slots from covered
balsa or the clear blister packs that hardware comes in. (Small
bubble canopies are a great resource.) Seal any openings between
the engine compartment and the fuselage.
Most servos today are quite water-resistant and tube-in-a-tube
pushrods seldom leak water into the fuselage, so you don’t need to
worry too much about them. The best way to seal the wing saddle
is with foam wing-saddle tape. Make sure the front and back as well
as both sides are sealed.
Hollow floats like to leak. Make it a practice to tip the airplane
nose down and then tail down to listen for water running back and
forth inside the floats. MA
—Jim Feldmann
A high-end version of the model-rescue boat! Bob Harts has
donated its use and himself all 17 years the local float-fly has
been taking place.
As does RC flying in general, float-flying appeals to all ages. Jim
Finch, who owns hobby shops in Redding and Eureka CA, helps
Logan Shaw, who ended his first float flight smiling.
Some sort of retrieval boat is required. Organized float-flys often
have sophisticated arrangements, but a canoe, a kayak such as the
one Charlie Hoisington (Redding CA) is using, or a two-man
inflatable will work as well.
Twin-rotor autogyro on floats, anyone? These models are
becoming extremely popular at indoor events. This one is built
from the GWS Slow Stick and equipped with GWS floats.
It is often said, “If it will fly on wheels, it will
fly on floats.” Richard Lucas (Fort Bragg
CA) learned that his rotating-wing (not
rotary wing) model flies either way.
E-flite’s Mini Ultra Stick is a terrific compact
electric aerobat, and it is just as good on
floats. You can throw it in your car’s trunk
and fly it almost anywhere there is water.
Some of the earliest full-scale airplanes were
sometimes put on floats. Balsa USA’s Taube
sports a set of tail-dragger floats, which take
some getting used to.
This is one of the safest recovery methods.
He doesn’t even have to lean over to pick
up the airplane. There is often as much
ingenuity in retrieval methods as there is
in the models themselves.
Scale seaplanes such as Great Planes’ Seawind can be a
handful on the water. Jim Feldmann made this pictureperfect
takeoff. He really enjoys this model.
The quickest way to start float-flying is to put floats on an old trainer you don’t
use much anymore. This Avistar flies as well on sheeted-foam floats as it did on
wheels. Keep the weight down with light floats and struts, and the model won’t
know they’re there.
42 MODEL AVIATION
Bruce Taylor and Nick Troehler share the duty of
bringing in a stalled Seamaster. Rule number one at a
float-fly: Don’t strafe the retrieval boat!
What Models Work Best?
Almost any airplane (or helicopter) will work on floats, but some
do better than others. Floats add a fair amount of weight to a model,
so you should start with a model that has a low wing loading, such as
a trainer or a light sport aircraft.
A low-wing airplane will work better on water than a high-wing
airplane will, simply because the wing is closer to the water and less
likely to be blown over in a crosswind taxi. Low-wingers are better
balanced for aerobatics too, with the floats below the wing and the
rest of the airplane above it.
High-wingers on floats are exceptionally stable in the air.
However, the extreme pendulum effect of the floats hanging down
under the fuselage makes turns and rolling maneuvers look strange.
Scale models tend to be harder to fly than sport models, and scale
floatplanes (such as the ubiquitous
Cub) are harder to fly than sport
floatplanes. The best-performing
and easiest-to-fly floatplane would
be something similar to a Sig Four-
Star kit or ARF, Goldberg Tiger kit
or ARF, or any of the Stick
variations. MA
—Jim Feldmann
• Set your airplane’s rudder for all the travel
you can get, and use exponential as needed to
calm it around center.
• Water rudders are optional. High-wing and
multiengine models usually need them; lowwing
models usually don’t.
• Rebalance the airplane after the floats (and
ventral fin, if used) are installed. If you need to
add balance weight, add it to the floats—not
the airplane.
Propellers: Wood propellers don’t mix with
water. The water that splashes into the
propeller will shred the wood before you even
get off the water. You can use any plastic
propellers, such as those from APC or Master
Airscrew.
The wind has a much greater effect on the
model when it’s taxiing on water than on land;
the water gives, where the ground stays put.
No matter which way the airplane is pointed, it
will move downwind unless you drive it some
other way. If there is a current in the water,
that will also have an effect. Taxiing on water
is similar to taxiing a tail-dragger on land.
When taxiing in a straight line, hold full
up-elevator and use approximately one-third
throttle to keep the back of the floats down in
the water and give the air rudder plenty of
steering authority.
If the floats come up on the step, slow
down until they settle back into the water. A
fast taxi on the step is a good technique for
windy conditions, but it requires practice. You
better take it slow.
When turning, slow to a walking pace,
release the elevator, and steer with the air
rudder, using bursts of throttle to kick the tail
around as needed. Hold full aileron toward the
wind to keep the upwind wing down.
Taking off From Water: Doing this is similar
to taking off from land with a tail-dragger. It is
actually easier to take off from water because
you can normally take off directly into the
wind, and you will need much less right
rudder to counteract torque.
Taxi out to the takeoff area, throttle back,
and let the airplane weather-vane into the
wind; you should still be holding full upelevator.
Advance the throttle smoothly while
releasing the elevator. The airplane will rise up
on top of the water and run along like a fast
boat.
When the airplane has reached flying
speed, add slight up-elevator and the airplane
will break the surface tension of the water and
take off. That “break” may cause a radical
pitch-up attitude, which you should quickly
correct to prevent a stall. Remember that
flying speed will need to be a bit faster
because of the floats’ weight.
Hold slight up-elevator until your model is
well out of ground effect. If you have a water
rudder, do not move the rudder stick during
the high-speed takeoff run. Water rudders are
incredibly effective at high speeds and can
easily cause a water loop.
Flying a Floatplane: Your model will fly
almost the same on floats as it did on wheels.
You will need a little up-trim on the elevator
to counteract the floats’ drag. The airplane is
heavier and draggier than it was on wheels, so
it will climb slower and come down faster.
Floats have a tendency to tame aircraft, so
you’ll find that aerobatics will be bigger and
smoother. The floats will create added lift and
actually make inverted and knife-edge
maneuvers easier. Be cautious when
performing spins; the added momentum of the
floats can make it more difficult to recover.
Landing a Floatplane on Water: Again, the
floatplane acts like a tail-dragger on land. All
water landings should be flared three-point
touchdowns. There is a great deal of drag
when the floats touch the water, and if you fly
the model onto the water in a wheel-landing
(tail high) attitude, there is a good chance that
it will flip upside down.
Following are some landing rules.
• Land directly into the wind, and try to land
downwind of your retrieval point.
• Keep your floatplane’s speed slightly faster
than you would for a ground landing.
• Fly down to a couple feet above the water
and then cut the throttle and flare by holding
altitude with the elevator. As the speed bleeds
off, the airplane will slowly settle onto the
water. Once on the water, the airplane will
slow more quickly than it does on land.
• Taxi back to shore in as straight a line as
possible to avoid taxiing crosswind. Keep that
upwind wing down by holding the aileron up.
• Try to wipe that silly grin off your face!
Everything is going to get wet if you flip
your model over or crash it. Fresh water will
not permanently damage your engine or radio
if you dry them out as soon as you get them
out of the water. Salt water, on the other hand,
will quickly destroy them.
If the worst happens, start the engine and
run it until it is good and hot, to evaporate any
water that is inside. Run it for at least five
minutes for a two-stroke and a whole tank of
fuel for a four-stroke. Then load up the engine
with a liberal dose of after-run oil.
Take the receiver, battery, switch, and any
servos that were underwater out of the
airplane and open them up. Blow out as much
water as you can, and then let them dry in the
sun.
Damage to electronics occurs when
mineral deposits form on metals. Lake water
is loaded with minerals. Using a soft plastic
brush and distilled water will help clean
electronics that might be dirty.
Both the engine and the radio should be
fine after the water has completely
evaporated. The model will typically survive
and can be repaired once the parts are dry.
Tips for Success: There are several things
you should pay attention to if you want your
first float-flying experience to be successful.
Avoid flying an underpowered model; you
will need a little more power for takeoffs from
water. This is not a problem for the average
sport model, but a low-powered trainer or
scale airplane might need more. Switching to
a larger-diameter, lower-pitch propeller may
help.
The rules of thumb regarding an improper
float setup are flexible, but there are limits.
Floats that are mounted too close together, not
parallel to each other or to the fuselage, or
with the step too far forward or too far back
will be problematic. The step should be under
or ahead of the CG.
Too much or not enough positive incidence
in the wing will make it difficult or impossible
for the model to take off from water.
Not having enough area in the fin and
rudder to offset the float area added in front of
the CG, which frequently happens with the J-3
Cub, will make the airplane unstable at takeoff
or during slow flight. If you don’t want to do
the math, add a subfin just to be safe.
If the airspeed on takeoff or landing is too
slow, the model will stall. Remember that you
need more speed to lift the extra weight of the
floats. If your airplane takes off too soon or
slows too much on the landing approach, it
will stall and everything will get wet. The full
throttle-and-full up method of takeoff seldom
works on the water.
Examine the float design carefully. The
shape and finish of the bottom of the floats is
critical. It is probably best to buy your first set
of floats. If you want to build them from
scratch, wait until after you know more about
them.
Flying from water is another great way to
enjoy model aircraft, and it is so much fun that
it is almost addictive. Try it; I bet you’ll like
it! MA
Jim Feldmann
[email protected]
Sources:
Ace Hobby Distributors
(949) 900-3300
www.acehobby.com
APC Propellers
(530) 661-0399
www.apcprop.com
Carl Goldberg Products
(217) 398-8970
www.carlgoldbergmodels.com
Great Planes Model Distributors
(217) 398-8970
www.greatplanes.com
Hangar 9
(800) 338-4639
www.hangar-9.com
Hobby Lobby International
(866) 933-5972
www.hobby-lobby.com
Master Airscrew
www.masterairscrew.com
Plane Fun Floats
www.geocities.com/planefunfloats
Sea Commander
(604) 485-2976
www.seacommander.com
Sig Manufacturing
(641) 623-5154
www.sigmfg.com
July 2008 43
Edition: Model Aviation - 2008/07
Page Numbers: 38,39,40,41,42,43
38 MODEL AVIATION
Two slightly overpowered Cubs look to be having so much fun playing follow the
leader around the lake that the crowds go wild. It is definitely habit-forming.
As the O.S. .46-powered Lanier Mariner gets lower, its reflection gets closer. The pilot backs off the throttle, gradually adding more
elevator for another touch-and-go on the cool waters of Lake Red Bluff in California.
Take advantage of
some of the nicest
flying sites around
BEFORE THERE WERE airports in every
town, large expanses of water were some of
the best places to land an airplane. The first
floatplanes were built only a few years after
the Wright brothers had their successes with
flight in the late 1800s and early 1900s. Before
World War II, the largest and most advanced
airliners were seaplanes. Even today, many
full-scale aircraft are fitted with floats to take
advantage of the many harbors, rivers, and
lakes around the world.
I enjoy flying models from water because
it combines the fun of boating, flying, and a
day at the lake. It is hard to describe the thrill
of a smooth takeoff and landing on water. Of
all the people I know who have successfully
tried water flying, none have given it up. If
there is a float-fly near you, go check it out.
Float-flying events are usually
noncompetitive. They are typically laid-back
STATE
SPORT
o f t h e
by
Jim Feldmann
Flying From
the Water
July 2008 39
family occasions with many interesting
airplanes and great camaraderie among people
who share the same interests. And the flying is
fun to watch.
Most float-fliers love to do touch-and-gos,
so the action is right in front of you. You will
see all kinds of models, from park flyers to
trainers to multiengine scale masterpieces. The
skill levels represented will range from
beginner to pro.
Getting Started: If you find yourself totally
inspired, look at the seaplanes that are
available. The Sig Sealane kit and the Ace
Hobby Distributors Seamaster 40 ARF are two
of the most popular.
If you just want to get your feet wet (as it
were), the easiest way is to put floats on your
favorite land airplane. Great Planes and
Hangar 9 offer float sets with struts that can be
used on almost any 40- to 60-size model.
Other vendors such as Sea Commander Floats,
Hobby Lobby, and Plane Fun Floats offer
excellent floats and float kits in a variety of
sizes to fit everything from park flyers to Giant
Scale models.
You don’t need to wait for the next floatfly
event. All you need is an uncrowded body
of water, a floatplane, and some way to
retrieve your model. You can’t always get the
airplane back to shore; unless you’re an
This Great Planes Super Stearman is
modified with a ventral fin to
compensate for the floats’ added side
area. It flew well on a piped gasoline
engine. Biplanes look so good on floats.
Isn’t that pretty? The giant-scale clipped-wing Cub on floats flies scalelike and hovers inches
off the surface. If you are really good, you can dip the rudder into the water. This pilot did!
Photos by Michael Brown
Olympic swimmer, you will need a boat, kayak, canoe, or something to
get out to the model and back.
Of course you should not fly where it is prohibited or where you
might endanger other people or property. For safety, wear a life vest in
that recovery boat and be sure to have someone with you in case of an
emergency.
The ideal water flying site will have a smooth beach or a dock where
you can launch and recover the aircraft, unobstructed overflight areas,
water that is smooth or with up to roughly a 2-inch chop, wind parallel
to the shoreline, and the sun behind you. Look around your area; you
may find that the local RC club already has a float-flying site chosen.
Making a Good Float Setup: Attaching and setting up floats is not
difficult, although you may need to modify the float mounting struts that
come with the set or make your own to fit your particular airplane. There
have been numerous technical articles describing it all in great detail.
The details are often conflicting, but don’t worry; you can be quite
far from the ideals without having serious problems. Following are the
accepted rules of thumb.
• The floats should be approximately 75% of the fuselage’s length from
the propeller to the rudder hinge line.
• The distance between the floats should be roughly 25% of the
wingspan.
• The float step should be directly under the airplane’s recommended
CG, plus or minus 1/2 inch or so.
• The top of the float should be at least 2 inches below the bottom of the
propeller arc.
• The top of the float should be positioned 0°-2° negative to the
horizontal stabilizer.
• There should be a spreader bar front and rear between the floats to
keep them parallel to each other at all times.
• If the combined area of your model’s vertical fin plus the part of the
rudder above the horizontal stabilizer is less than 8% of the wing area,
add a ventral fin to bring the total area up to 8%-10%.
The Laddie Mikulasko-designed Northstar
as an amphibian. Available as a kit from
Balsa USA, it handles great with a .46 twostroke
and is super-groovy in the air. It is
unlikely that this model will flip in a
crosswind.
40 MODEL AVIATION
Sam Arrigo’s (Grants Pass OR) Seamaster
was built from a kit and covered in an
outstanding high-visibility color scheme.
Seaplanes are another way to fly from
water, and they perform the same as lightly
loaded sport models.
This O.S. .91-powered World Models
Super Sports Senior on 120-size floats is
smooth, stable, and easy to fly with or
without floats. Lightly loaded, low-wing
sport models make some of the nicestflying
floatplanes.
The Herr Aqua Star is a three-channel, 1/2A
design that can fly around in small ponds
and light winds. Modifying it for electric
power is a snap.
A Midwest Aero-Star on Slocan floats
taxis back from a flight. Don’t let the
overcast skies stop you from flying; floats
make a model more stable and easier to
see in the air.
A typical float-fly flightline. Some have big crowds and some have
only a few club members and friends. Big crowds mean more
diversity, and small groups mean more flight time. Both are great!
Airplanes such as this Pacific Aeromodel Lazy Days three-channel
electric on GWS floats flies so slowly and gently that we often refer
to them as “lawn-chair fliers.” They are limited to no-wind
conditions, though.
Scale floatplanes such as Hangar 9’s Cessna can fly well; they
don’t have to be Cubs. The heavier they are, the longer the
takeoff run they’ll need.
July 2008 41
Water-Proofing
Your Investment
In normal use on
water, you need to
protect your model and
equipment against spray
and splashes. Water will
try to get under the
covering and lift it. It can
also cause mildew to grow
inside the airframe.
A few drops of water
inside the fuselage are not
a flight problem. However, as it runs back and forth, a lot of it can
cause the CG to move. In the worst case it could stop the radio
from working. Low-wing airplanes are better in this regard, because
any water that gets into the fuselage will tend to run back out
through the wing saddle.
Make sure the radio equipment is not mounted on the fuselage
floor; that’s where water accumulates. Go over the airplane and
seal all exposed wood with thin cyanoacrylate or epoxy. Make it
part of your regular preflight routine to examine the covering and
iron down any loose seams.
Use silicone sealant to close any openings around externally
mounted servos. If you have hatch-mounted servos with a large
slot for the arm, make a small shield for the slots from covered
balsa or the clear blister packs that hardware comes in. (Small
bubble canopies are a great resource.) Seal any openings between
the engine compartment and the fuselage.
Most servos today are quite water-resistant and tube-in-a-tube
pushrods seldom leak water into the fuselage, so you don’t need to
worry too much about them. The best way to seal the wing saddle
is with foam wing-saddle tape. Make sure the front and back as well
as both sides are sealed.
Hollow floats like to leak. Make it a practice to tip the airplane
nose down and then tail down to listen for water running back and
forth inside the floats. MA
—Jim Feldmann
A high-end version of the model-rescue boat! Bob Harts has
donated its use and himself all 17 years the local float-fly has
been taking place.
As does RC flying in general, float-flying appeals to all ages. Jim
Finch, who owns hobby shops in Redding and Eureka CA, helps
Logan Shaw, who ended his first float flight smiling.
Some sort of retrieval boat is required. Organized float-flys often
have sophisticated arrangements, but a canoe, a kayak such as the
one Charlie Hoisington (Redding CA) is using, or a two-man
inflatable will work as well.
Twin-rotor autogyro on floats, anyone? These models are
becoming extremely popular at indoor events. This one is built
from the GWS Slow Stick and equipped with GWS floats.
It is often said, “If it will fly on wheels, it will
fly on floats.” Richard Lucas (Fort Bragg
CA) learned that his rotating-wing (not
rotary wing) model flies either way.
E-flite’s Mini Ultra Stick is a terrific compact
electric aerobat, and it is just as good on
floats. You can throw it in your car’s trunk
and fly it almost anywhere there is water.
Some of the earliest full-scale airplanes were
sometimes put on floats. Balsa USA’s Taube
sports a set of tail-dragger floats, which take
some getting used to.
This is one of the safest recovery methods.
He doesn’t even have to lean over to pick
up the airplane. There is often as much
ingenuity in retrieval methods as there is
in the models themselves.
Scale seaplanes such as Great Planes’ Seawind can be a
handful on the water. Jim Feldmann made this pictureperfect
takeoff. He really enjoys this model.
The quickest way to start float-flying is to put floats on an old trainer you don’t
use much anymore. This Avistar flies as well on sheeted-foam floats as it did on
wheels. Keep the weight down with light floats and struts, and the model won’t
know they’re there.
42 MODEL AVIATION
Bruce Taylor and Nick Troehler share the duty of
bringing in a stalled Seamaster. Rule number one at a
float-fly: Don’t strafe the retrieval boat!
What Models Work Best?
Almost any airplane (or helicopter) will work on floats, but some
do better than others. Floats add a fair amount of weight to a model,
so you should start with a model that has a low wing loading, such as
a trainer or a light sport aircraft.
A low-wing airplane will work better on water than a high-wing
airplane will, simply because the wing is closer to the water and less
likely to be blown over in a crosswind taxi. Low-wingers are better
balanced for aerobatics too, with the floats below the wing and the
rest of the airplane above it.
High-wingers on floats are exceptionally stable in the air.
However, the extreme pendulum effect of the floats hanging down
under the fuselage makes turns and rolling maneuvers look strange.
Scale models tend to be harder to fly than sport models, and scale
floatplanes (such as the ubiquitous
Cub) are harder to fly than sport
floatplanes. The best-performing
and easiest-to-fly floatplane would
be something similar to a Sig Four-
Star kit or ARF, Goldberg Tiger kit
or ARF, or any of the Stick
variations. MA
—Jim Feldmann
• Set your airplane’s rudder for all the travel
you can get, and use exponential as needed to
calm it around center.
• Water rudders are optional. High-wing and
multiengine models usually need them; lowwing
models usually don’t.
• Rebalance the airplane after the floats (and
ventral fin, if used) are installed. If you need to
add balance weight, add it to the floats—not
the airplane.
Propellers: Wood propellers don’t mix with
water. The water that splashes into the
propeller will shred the wood before you even
get off the water. You can use any plastic
propellers, such as those from APC or Master
Airscrew.
The wind has a much greater effect on the
model when it’s taxiing on water than on land;
the water gives, where the ground stays put.
No matter which way the airplane is pointed, it
will move downwind unless you drive it some
other way. If there is a current in the water,
that will also have an effect. Taxiing on water
is similar to taxiing a tail-dragger on land.
When taxiing in a straight line, hold full
up-elevator and use approximately one-third
throttle to keep the back of the floats down in
the water and give the air rudder plenty of
steering authority.
If the floats come up on the step, slow
down until they settle back into the water. A
fast taxi on the step is a good technique for
windy conditions, but it requires practice. You
better take it slow.
When turning, slow to a walking pace,
release the elevator, and steer with the air
rudder, using bursts of throttle to kick the tail
around as needed. Hold full aileron toward the
wind to keep the upwind wing down.
Taking off From Water: Doing this is similar
to taking off from land with a tail-dragger. It is
actually easier to take off from water because
you can normally take off directly into the
wind, and you will need much less right
rudder to counteract torque.
Taxi out to the takeoff area, throttle back,
and let the airplane weather-vane into the
wind; you should still be holding full upelevator.
Advance the throttle smoothly while
releasing the elevator. The airplane will rise up
on top of the water and run along like a fast
boat.
When the airplane has reached flying
speed, add slight up-elevator and the airplane
will break the surface tension of the water and
take off. That “break” may cause a radical
pitch-up attitude, which you should quickly
correct to prevent a stall. Remember that
flying speed will need to be a bit faster
because of the floats’ weight.
Hold slight up-elevator until your model is
well out of ground effect. If you have a water
rudder, do not move the rudder stick during
the high-speed takeoff run. Water rudders are
incredibly effective at high speeds and can
easily cause a water loop.
Flying a Floatplane: Your model will fly
almost the same on floats as it did on wheels.
You will need a little up-trim on the elevator
to counteract the floats’ drag. The airplane is
heavier and draggier than it was on wheels, so
it will climb slower and come down faster.
Floats have a tendency to tame aircraft, so
you’ll find that aerobatics will be bigger and
smoother. The floats will create added lift and
actually make inverted and knife-edge
maneuvers easier. Be cautious when
performing spins; the added momentum of the
floats can make it more difficult to recover.
Landing a Floatplane on Water: Again, the
floatplane acts like a tail-dragger on land. All
water landings should be flared three-point
touchdowns. There is a great deal of drag
when the floats touch the water, and if you fly
the model onto the water in a wheel-landing
(tail high) attitude, there is a good chance that
it will flip upside down.
Following are some landing rules.
• Land directly into the wind, and try to land
downwind of your retrieval point.
• Keep your floatplane’s speed slightly faster
than you would for a ground landing.
• Fly down to a couple feet above the water
and then cut the throttle and flare by holding
altitude with the elevator. As the speed bleeds
off, the airplane will slowly settle onto the
water. Once on the water, the airplane will
slow more quickly than it does on land.
• Taxi back to shore in as straight a line as
possible to avoid taxiing crosswind. Keep that
upwind wing down by holding the aileron up.
• Try to wipe that silly grin off your face!
Everything is going to get wet if you flip
your model over or crash it. Fresh water will
not permanently damage your engine or radio
if you dry them out as soon as you get them
out of the water. Salt water, on the other hand,
will quickly destroy them.
If the worst happens, start the engine and
run it until it is good and hot, to evaporate any
water that is inside. Run it for at least five
minutes for a two-stroke and a whole tank of
fuel for a four-stroke. Then load up the engine
with a liberal dose of after-run oil.
Take the receiver, battery, switch, and any
servos that were underwater out of the
airplane and open them up. Blow out as much
water as you can, and then let them dry in the
sun.
Damage to electronics occurs when
mineral deposits form on metals. Lake water
is loaded with minerals. Using a soft plastic
brush and distilled water will help clean
electronics that might be dirty.
Both the engine and the radio should be
fine after the water has completely
evaporated. The model will typically survive
and can be repaired once the parts are dry.
Tips for Success: There are several things
you should pay attention to if you want your
first float-flying experience to be successful.
Avoid flying an underpowered model; you
will need a little more power for takeoffs from
water. This is not a problem for the average
sport model, but a low-powered trainer or
scale airplane might need more. Switching to
a larger-diameter, lower-pitch propeller may
help.
The rules of thumb regarding an improper
float setup are flexible, but there are limits.
Floats that are mounted too close together, not
parallel to each other or to the fuselage, or
with the step too far forward or too far back
will be problematic. The step should be under
or ahead of the CG.
Too much or not enough positive incidence
in the wing will make it difficult or impossible
for the model to take off from water.
Not having enough area in the fin and
rudder to offset the float area added in front of
the CG, which frequently happens with the J-3
Cub, will make the airplane unstable at takeoff
or during slow flight. If you don’t want to do
the math, add a subfin just to be safe.
If the airspeed on takeoff or landing is too
slow, the model will stall. Remember that you
need more speed to lift the extra weight of the
floats. If your airplane takes off too soon or
slows too much on the landing approach, it
will stall and everything will get wet. The full
throttle-and-full up method of takeoff seldom
works on the water.
Examine the float design carefully. The
shape and finish of the bottom of the floats is
critical. It is probably best to buy your first set
of floats. If you want to build them from
scratch, wait until after you know more about
them.
Flying from water is another great way to
enjoy model aircraft, and it is so much fun that
it is almost addictive. Try it; I bet you’ll like
it! MA
Jim Feldmann
[email protected]
Sources:
Ace Hobby Distributors
(949) 900-3300
www.acehobby.com
APC Propellers
(530) 661-0399
www.apcprop.com
Carl Goldberg Products
(217) 398-8970
www.carlgoldbergmodels.com
Great Planes Model Distributors
(217) 398-8970
www.greatplanes.com
Hangar 9
(800) 338-4639
www.hangar-9.com
Hobby Lobby International
(866) 933-5972
www.hobby-lobby.com
Master Airscrew
www.masterairscrew.com
Plane Fun Floats
www.geocities.com/planefunfloats
Sea Commander
(604) 485-2976
www.seacommander.com
Sig Manufacturing
(641) 623-5154
www.sigmfg.com
July 2008 43
Edition: Model Aviation - 2008/07
Page Numbers: 38,39,40,41,42,43
38 MODEL AVIATION
Two slightly overpowered Cubs look to be having so much fun playing follow the
leader around the lake that the crowds go wild. It is definitely habit-forming.
As the O.S. .46-powered Lanier Mariner gets lower, its reflection gets closer. The pilot backs off the throttle, gradually adding more
elevator for another touch-and-go on the cool waters of Lake Red Bluff in California.
Take advantage of
some of the nicest
flying sites around
BEFORE THERE WERE airports in every
town, large expanses of water were some of
the best places to land an airplane. The first
floatplanes were built only a few years after
the Wright brothers had their successes with
flight in the late 1800s and early 1900s. Before
World War II, the largest and most advanced
airliners were seaplanes. Even today, many
full-scale aircraft are fitted with floats to take
advantage of the many harbors, rivers, and
lakes around the world.
I enjoy flying models from water because
it combines the fun of boating, flying, and a
day at the lake. It is hard to describe the thrill
of a smooth takeoff and landing on water. Of
all the people I know who have successfully
tried water flying, none have given it up. If
there is a float-fly near you, go check it out.
Float-flying events are usually
noncompetitive. They are typically laid-back
STATE
SPORT
o f t h e
by
Jim Feldmann
Flying From
the Water
July 2008 39
family occasions with many interesting
airplanes and great camaraderie among people
who share the same interests. And the flying is
fun to watch.
Most float-fliers love to do touch-and-gos,
so the action is right in front of you. You will
see all kinds of models, from park flyers to
trainers to multiengine scale masterpieces. The
skill levels represented will range from
beginner to pro.
Getting Started: If you find yourself totally
inspired, look at the seaplanes that are
available. The Sig Sealane kit and the Ace
Hobby Distributors Seamaster 40 ARF are two
of the most popular.
If you just want to get your feet wet (as it
were), the easiest way is to put floats on your
favorite land airplane. Great Planes and
Hangar 9 offer float sets with struts that can be
used on almost any 40- to 60-size model.
Other vendors such as Sea Commander Floats,
Hobby Lobby, and Plane Fun Floats offer
excellent floats and float kits in a variety of
sizes to fit everything from park flyers to Giant
Scale models.
You don’t need to wait for the next floatfly
event. All you need is an uncrowded body
of water, a floatplane, and some way to
retrieve your model. You can’t always get the
airplane back to shore; unless you’re an
This Great Planes Super Stearman is
modified with a ventral fin to
compensate for the floats’ added side
area. It flew well on a piped gasoline
engine. Biplanes look so good on floats.
Isn’t that pretty? The giant-scale clipped-wing Cub on floats flies scalelike and hovers inches
off the surface. If you are really good, you can dip the rudder into the water. This pilot did!
Photos by Michael Brown
Olympic swimmer, you will need a boat, kayak, canoe, or something to
get out to the model and back.
Of course you should not fly where it is prohibited or where you
might endanger other people or property. For safety, wear a life vest in
that recovery boat and be sure to have someone with you in case of an
emergency.
The ideal water flying site will have a smooth beach or a dock where
you can launch and recover the aircraft, unobstructed overflight areas,
water that is smooth or with up to roughly a 2-inch chop, wind parallel
to the shoreline, and the sun behind you. Look around your area; you
may find that the local RC club already has a float-flying site chosen.
Making a Good Float Setup: Attaching and setting up floats is not
difficult, although you may need to modify the float mounting struts that
come with the set or make your own to fit your particular airplane. There
have been numerous technical articles describing it all in great detail.
The details are often conflicting, but don’t worry; you can be quite
far from the ideals without having serious problems. Following are the
accepted rules of thumb.
• The floats should be approximately 75% of the fuselage’s length from
the propeller to the rudder hinge line.
• The distance between the floats should be roughly 25% of the
wingspan.
• The float step should be directly under the airplane’s recommended
CG, plus or minus 1/2 inch or so.
• The top of the float should be at least 2 inches below the bottom of the
propeller arc.
• The top of the float should be positioned 0°-2° negative to the
horizontal stabilizer.
• There should be a spreader bar front and rear between the floats to
keep them parallel to each other at all times.
• If the combined area of your model’s vertical fin plus the part of the
rudder above the horizontal stabilizer is less than 8% of the wing area,
add a ventral fin to bring the total area up to 8%-10%.
The Laddie Mikulasko-designed Northstar
as an amphibian. Available as a kit from
Balsa USA, it handles great with a .46 twostroke
and is super-groovy in the air. It is
unlikely that this model will flip in a
crosswind.
40 MODEL AVIATION
Sam Arrigo’s (Grants Pass OR) Seamaster
was built from a kit and covered in an
outstanding high-visibility color scheme.
Seaplanes are another way to fly from
water, and they perform the same as lightly
loaded sport models.
This O.S. .91-powered World Models
Super Sports Senior on 120-size floats is
smooth, stable, and easy to fly with or
without floats. Lightly loaded, low-wing
sport models make some of the nicestflying
floatplanes.
The Herr Aqua Star is a three-channel, 1/2A
design that can fly around in small ponds
and light winds. Modifying it for electric
power is a snap.
A Midwest Aero-Star on Slocan floats
taxis back from a flight. Don’t let the
overcast skies stop you from flying; floats
make a model more stable and easier to
see in the air.
A typical float-fly flightline. Some have big crowds and some have
only a few club members and friends. Big crowds mean more
diversity, and small groups mean more flight time. Both are great!
Airplanes such as this Pacific Aeromodel Lazy Days three-channel
electric on GWS floats flies so slowly and gently that we often refer
to them as “lawn-chair fliers.” They are limited to no-wind
conditions, though.
Scale floatplanes such as Hangar 9’s Cessna can fly well; they
don’t have to be Cubs. The heavier they are, the longer the
takeoff run they’ll need.
July 2008 41
Water-Proofing
Your Investment
In normal use on
water, you need to
protect your model and
equipment against spray
and splashes. Water will
try to get under the
covering and lift it. It can
also cause mildew to grow
inside the airframe.
A few drops of water
inside the fuselage are not
a flight problem. However, as it runs back and forth, a lot of it can
cause the CG to move. In the worst case it could stop the radio
from working. Low-wing airplanes are better in this regard, because
any water that gets into the fuselage will tend to run back out
through the wing saddle.
Make sure the radio equipment is not mounted on the fuselage
floor; that’s where water accumulates. Go over the airplane and
seal all exposed wood with thin cyanoacrylate or epoxy. Make it
part of your regular preflight routine to examine the covering and
iron down any loose seams.
Use silicone sealant to close any openings around externally
mounted servos. If you have hatch-mounted servos with a large
slot for the arm, make a small shield for the slots from covered
balsa or the clear blister packs that hardware comes in. (Small
bubble canopies are a great resource.) Seal any openings between
the engine compartment and the fuselage.
Most servos today are quite water-resistant and tube-in-a-tube
pushrods seldom leak water into the fuselage, so you don’t need to
worry too much about them. The best way to seal the wing saddle
is with foam wing-saddle tape. Make sure the front and back as well
as both sides are sealed.
Hollow floats like to leak. Make it a practice to tip the airplane
nose down and then tail down to listen for water running back and
forth inside the floats. MA
—Jim Feldmann
A high-end version of the model-rescue boat! Bob Harts has
donated its use and himself all 17 years the local float-fly has
been taking place.
As does RC flying in general, float-flying appeals to all ages. Jim
Finch, who owns hobby shops in Redding and Eureka CA, helps
Logan Shaw, who ended his first float flight smiling.
Some sort of retrieval boat is required. Organized float-flys often
have sophisticated arrangements, but a canoe, a kayak such as the
one Charlie Hoisington (Redding CA) is using, or a two-man
inflatable will work as well.
Twin-rotor autogyro on floats, anyone? These models are
becoming extremely popular at indoor events. This one is built
from the GWS Slow Stick and equipped with GWS floats.
It is often said, “If it will fly on wheels, it will
fly on floats.” Richard Lucas (Fort Bragg
CA) learned that his rotating-wing (not
rotary wing) model flies either way.
E-flite’s Mini Ultra Stick is a terrific compact
electric aerobat, and it is just as good on
floats. You can throw it in your car’s trunk
and fly it almost anywhere there is water.
Some of the earliest full-scale airplanes were
sometimes put on floats. Balsa USA’s Taube
sports a set of tail-dragger floats, which take
some getting used to.
This is one of the safest recovery methods.
He doesn’t even have to lean over to pick
up the airplane. There is often as much
ingenuity in retrieval methods as there is
in the models themselves.
Scale seaplanes such as Great Planes’ Seawind can be a
handful on the water. Jim Feldmann made this pictureperfect
takeoff. He really enjoys this model.
The quickest way to start float-flying is to put floats on an old trainer you don’t
use much anymore. This Avistar flies as well on sheeted-foam floats as it did on
wheels. Keep the weight down with light floats and struts, and the model won’t
know they’re there.
42 MODEL AVIATION
Bruce Taylor and Nick Troehler share the duty of
bringing in a stalled Seamaster. Rule number one at a
float-fly: Don’t strafe the retrieval boat!
What Models Work Best?
Almost any airplane (or helicopter) will work on floats, but some
do better than others. Floats add a fair amount of weight to a model,
so you should start with a model that has a low wing loading, such as
a trainer or a light sport aircraft.
A low-wing airplane will work better on water than a high-wing
airplane will, simply because the wing is closer to the water and less
likely to be blown over in a crosswind taxi. Low-wingers are better
balanced for aerobatics too, with the floats below the wing and the
rest of the airplane above it.
High-wingers on floats are exceptionally stable in the air.
However, the extreme pendulum effect of the floats hanging down
under the fuselage makes turns and rolling maneuvers look strange.
Scale models tend to be harder to fly than sport models, and scale
floatplanes (such as the ubiquitous
Cub) are harder to fly than sport
floatplanes. The best-performing
and easiest-to-fly floatplane would
be something similar to a Sig Four-
Star kit or ARF, Goldberg Tiger kit
or ARF, or any of the Stick
variations. MA
—Jim Feldmann
• Set your airplane’s rudder for all the travel
you can get, and use exponential as needed to
calm it around center.
• Water rudders are optional. High-wing and
multiengine models usually need them; lowwing
models usually don’t.
• Rebalance the airplane after the floats (and
ventral fin, if used) are installed. If you need to
add balance weight, add it to the floats—not
the airplane.
Propellers: Wood propellers don’t mix with
water. The water that splashes into the
propeller will shred the wood before you even
get off the water. You can use any plastic
propellers, such as those from APC or Master
Airscrew.
The wind has a much greater effect on the
model when it’s taxiing on water than on land;
the water gives, where the ground stays put.
No matter which way the airplane is pointed, it
will move downwind unless you drive it some
other way. If there is a current in the water,
that will also have an effect. Taxiing on water
is similar to taxiing a tail-dragger on land.
When taxiing in a straight line, hold full
up-elevator and use approximately one-third
throttle to keep the back of the floats down in
the water and give the air rudder plenty of
steering authority.
If the floats come up on the step, slow
down until they settle back into the water. A
fast taxi on the step is a good technique for
windy conditions, but it requires practice. You
better take it slow.
When turning, slow to a walking pace,
release the elevator, and steer with the air
rudder, using bursts of throttle to kick the tail
around as needed. Hold full aileron toward the
wind to keep the upwind wing down.
Taking off From Water: Doing this is similar
to taking off from land with a tail-dragger. It is
actually easier to take off from water because
you can normally take off directly into the
wind, and you will need much less right
rudder to counteract torque.
Taxi out to the takeoff area, throttle back,
and let the airplane weather-vane into the
wind; you should still be holding full upelevator.
Advance the throttle smoothly while
releasing the elevator. The airplane will rise up
on top of the water and run along like a fast
boat.
When the airplane has reached flying
speed, add slight up-elevator and the airplane
will break the surface tension of the water and
take off. That “break” may cause a radical
pitch-up attitude, which you should quickly
correct to prevent a stall. Remember that
flying speed will need to be a bit faster
because of the floats’ weight.
Hold slight up-elevator until your model is
well out of ground effect. If you have a water
rudder, do not move the rudder stick during
the high-speed takeoff run. Water rudders are
incredibly effective at high speeds and can
easily cause a water loop.
Flying a Floatplane: Your model will fly
almost the same on floats as it did on wheels.
You will need a little up-trim on the elevator
to counteract the floats’ drag. The airplane is
heavier and draggier than it was on wheels, so
it will climb slower and come down faster.
Floats have a tendency to tame aircraft, so
you’ll find that aerobatics will be bigger and
smoother. The floats will create added lift and
actually make inverted and knife-edge
maneuvers easier. Be cautious when
performing spins; the added momentum of the
floats can make it more difficult to recover.
Landing a Floatplane on Water: Again, the
floatplane acts like a tail-dragger on land. All
water landings should be flared three-point
touchdowns. There is a great deal of drag
when the floats touch the water, and if you fly
the model onto the water in a wheel-landing
(tail high) attitude, there is a good chance that
it will flip upside down.
Following are some landing rules.
• Land directly into the wind, and try to land
downwind of your retrieval point.
• Keep your floatplane’s speed slightly faster
than you would for a ground landing.
• Fly down to a couple feet above the water
and then cut the throttle and flare by holding
altitude with the elevator. As the speed bleeds
off, the airplane will slowly settle onto the
water. Once on the water, the airplane will
slow more quickly than it does on land.
• Taxi back to shore in as straight a line as
possible to avoid taxiing crosswind. Keep that
upwind wing down by holding the aileron up.
• Try to wipe that silly grin off your face!
Everything is going to get wet if you flip
your model over or crash it. Fresh water will
not permanently damage your engine or radio
if you dry them out as soon as you get them
out of the water. Salt water, on the other hand,
will quickly destroy them.
If the worst happens, start the engine and
run it until it is good and hot, to evaporate any
water that is inside. Run it for at least five
minutes for a two-stroke and a whole tank of
fuel for a four-stroke. Then load up the engine
with a liberal dose of after-run oil.
Take the receiver, battery, switch, and any
servos that were underwater out of the
airplane and open them up. Blow out as much
water as you can, and then let them dry in the
sun.
Damage to electronics occurs when
mineral deposits form on metals. Lake water
is loaded with minerals. Using a soft plastic
brush and distilled water will help clean
electronics that might be dirty.
Both the engine and the radio should be
fine after the water has completely
evaporated. The model will typically survive
and can be repaired once the parts are dry.
Tips for Success: There are several things
you should pay attention to if you want your
first float-flying experience to be successful.
Avoid flying an underpowered model; you
will need a little more power for takeoffs from
water. This is not a problem for the average
sport model, but a low-powered trainer or
scale airplane might need more. Switching to
a larger-diameter, lower-pitch propeller may
help.
The rules of thumb regarding an improper
float setup are flexible, but there are limits.
Floats that are mounted too close together, not
parallel to each other or to the fuselage, or
with the step too far forward or too far back
will be problematic. The step should be under
or ahead of the CG.
Too much or not enough positive incidence
in the wing will make it difficult or impossible
for the model to take off from water.
Not having enough area in the fin and
rudder to offset the float area added in front of
the CG, which frequently happens with the J-3
Cub, will make the airplane unstable at takeoff
or during slow flight. If you don’t want to do
the math, add a subfin just to be safe.
If the airspeed on takeoff or landing is too
slow, the model will stall. Remember that you
need more speed to lift the extra weight of the
floats. If your airplane takes off too soon or
slows too much on the landing approach, it
will stall and everything will get wet. The full
throttle-and-full up method of takeoff seldom
works on the water.
Examine the float design carefully. The
shape and finish of the bottom of the floats is
critical. It is probably best to buy your first set
of floats. If you want to build them from
scratch, wait until after you know more about
them.
Flying from water is another great way to
enjoy model aircraft, and it is so much fun that
it is almost addictive. Try it; I bet you’ll like
it! MA
Jim Feldmann
[email protected]
Sources:
Ace Hobby Distributors
(949) 900-3300
www.acehobby.com
APC Propellers
(530) 661-0399
www.apcprop.com
Carl Goldberg Products
(217) 398-8970
www.carlgoldbergmodels.com
Great Planes Model Distributors
(217) 398-8970
www.greatplanes.com
Hangar 9
(800) 338-4639
www.hangar-9.com
Hobby Lobby International
(866) 933-5972
www.hobby-lobby.com
Master Airscrew
www.masterairscrew.com
Plane Fun Floats
www.geocities.com/planefunfloats
Sea Commander
(604) 485-2976
www.seacommander.com
Sig Manufacturing
(641) 623-5154
www.sigmfg.com
July 2008 43
Edition: Model Aviation - 2008/07
Page Numbers: 38,39,40,41,42,43
38 MODEL AVIATION
Two slightly overpowered Cubs look to be having so much fun playing follow the
leader around the lake that the crowds go wild. It is definitely habit-forming.
As the O.S. .46-powered Lanier Mariner gets lower, its reflection gets closer. The pilot backs off the throttle, gradually adding more
elevator for another touch-and-go on the cool waters of Lake Red Bluff in California.
Take advantage of
some of the nicest
flying sites around
BEFORE THERE WERE airports in every
town, large expanses of water were some of
the best places to land an airplane. The first
floatplanes were built only a few years after
the Wright brothers had their successes with
flight in the late 1800s and early 1900s. Before
World War II, the largest and most advanced
airliners were seaplanes. Even today, many
full-scale aircraft are fitted with floats to take
advantage of the many harbors, rivers, and
lakes around the world.
I enjoy flying models from water because
it combines the fun of boating, flying, and a
day at the lake. It is hard to describe the thrill
of a smooth takeoff and landing on water. Of
all the people I know who have successfully
tried water flying, none have given it up. If
there is a float-fly near you, go check it out.
Float-flying events are usually
noncompetitive. They are typically laid-back
STATE
SPORT
o f t h e
by
Jim Feldmann
Flying From
the Water
July 2008 39
family occasions with many interesting
airplanes and great camaraderie among people
who share the same interests. And the flying is
fun to watch.
Most float-fliers love to do touch-and-gos,
so the action is right in front of you. You will
see all kinds of models, from park flyers to
trainers to multiengine scale masterpieces. The
skill levels represented will range from
beginner to pro.
Getting Started: If you find yourself totally
inspired, look at the seaplanes that are
available. The Sig Sealane kit and the Ace
Hobby Distributors Seamaster 40 ARF are two
of the most popular.
If you just want to get your feet wet (as it
were), the easiest way is to put floats on your
favorite land airplane. Great Planes and
Hangar 9 offer float sets with struts that can be
used on almost any 40- to 60-size model.
Other vendors such as Sea Commander Floats,
Hobby Lobby, and Plane Fun Floats offer
excellent floats and float kits in a variety of
sizes to fit everything from park flyers to Giant
Scale models.
You don’t need to wait for the next floatfly
event. All you need is an uncrowded body
of water, a floatplane, and some way to
retrieve your model. You can’t always get the
airplane back to shore; unless you’re an
This Great Planes Super Stearman is
modified with a ventral fin to
compensate for the floats’ added side
area. It flew well on a piped gasoline
engine. Biplanes look so good on floats.
Isn’t that pretty? The giant-scale clipped-wing Cub on floats flies scalelike and hovers inches
off the surface. If you are really good, you can dip the rudder into the water. This pilot did!
Photos by Michael Brown
Olympic swimmer, you will need a boat, kayak, canoe, or something to
get out to the model and back.
Of course you should not fly where it is prohibited or where you
might endanger other people or property. For safety, wear a life vest in
that recovery boat and be sure to have someone with you in case of an
emergency.
The ideal water flying site will have a smooth beach or a dock where
you can launch and recover the aircraft, unobstructed overflight areas,
water that is smooth or with up to roughly a 2-inch chop, wind parallel
to the shoreline, and the sun behind you. Look around your area; you
may find that the local RC club already has a float-flying site chosen.
Making a Good Float Setup: Attaching and setting up floats is not
difficult, although you may need to modify the float mounting struts that
come with the set or make your own to fit your particular airplane. There
have been numerous technical articles describing it all in great detail.
The details are often conflicting, but don’t worry; you can be quite
far from the ideals without having serious problems. Following are the
accepted rules of thumb.
• The floats should be approximately 75% of the fuselage’s length from
the propeller to the rudder hinge line.
• The distance between the floats should be roughly 25% of the
wingspan.
• The float step should be directly under the airplane’s recommended
CG, plus or minus 1/2 inch or so.
• The top of the float should be at least 2 inches below the bottom of the
propeller arc.
• The top of the float should be positioned 0°-2° negative to the
horizontal stabilizer.
• There should be a spreader bar front and rear between the floats to
keep them parallel to each other at all times.
• If the combined area of your model’s vertical fin plus the part of the
rudder above the horizontal stabilizer is less than 8% of the wing area,
add a ventral fin to bring the total area up to 8%-10%.
The Laddie Mikulasko-designed Northstar
as an amphibian. Available as a kit from
Balsa USA, it handles great with a .46 twostroke
and is super-groovy in the air. It is
unlikely that this model will flip in a
crosswind.
40 MODEL AVIATION
Sam Arrigo’s (Grants Pass OR) Seamaster
was built from a kit and covered in an
outstanding high-visibility color scheme.
Seaplanes are another way to fly from
water, and they perform the same as lightly
loaded sport models.
This O.S. .91-powered World Models
Super Sports Senior on 120-size floats is
smooth, stable, and easy to fly with or
without floats. Lightly loaded, low-wing
sport models make some of the nicestflying
floatplanes.
The Herr Aqua Star is a three-channel, 1/2A
design that can fly around in small ponds
and light winds. Modifying it for electric
power is a snap.
A Midwest Aero-Star on Slocan floats
taxis back from a flight. Don’t let the
overcast skies stop you from flying; floats
make a model more stable and easier to
see in the air.
A typical float-fly flightline. Some have big crowds and some have
only a few club members and friends. Big crowds mean more
diversity, and small groups mean more flight time. Both are great!
Airplanes such as this Pacific Aeromodel Lazy Days three-channel
electric on GWS floats flies so slowly and gently that we often refer
to them as “lawn-chair fliers.” They are limited to no-wind
conditions, though.
Scale floatplanes such as Hangar 9’s Cessna can fly well; they
don’t have to be Cubs. The heavier they are, the longer the
takeoff run they’ll need.
July 2008 41
Water-Proofing
Your Investment
In normal use on
water, you need to
protect your model and
equipment against spray
and splashes. Water will
try to get under the
covering and lift it. It can
also cause mildew to grow
inside the airframe.
A few drops of water
inside the fuselage are not
a flight problem. However, as it runs back and forth, a lot of it can
cause the CG to move. In the worst case it could stop the radio
from working. Low-wing airplanes are better in this regard, because
any water that gets into the fuselage will tend to run back out
through the wing saddle.
Make sure the radio equipment is not mounted on the fuselage
floor; that’s where water accumulates. Go over the airplane and
seal all exposed wood with thin cyanoacrylate or epoxy. Make it
part of your regular preflight routine to examine the covering and
iron down any loose seams.
Use silicone sealant to close any openings around externally
mounted servos. If you have hatch-mounted servos with a large
slot for the arm, make a small shield for the slots from covered
balsa or the clear blister packs that hardware comes in. (Small
bubble canopies are a great resource.) Seal any openings between
the engine compartment and the fuselage.
Most servos today are quite water-resistant and tube-in-a-tube
pushrods seldom leak water into the fuselage, so you don’t need to
worry too much about them. The best way to seal the wing saddle
is with foam wing-saddle tape. Make sure the front and back as well
as both sides are sealed.
Hollow floats like to leak. Make it a practice to tip the airplane
nose down and then tail down to listen for water running back and
forth inside the floats. MA
—Jim Feldmann
A high-end version of the model-rescue boat! Bob Harts has
donated its use and himself all 17 years the local float-fly has
been taking place.
As does RC flying in general, float-flying appeals to all ages. Jim
Finch, who owns hobby shops in Redding and Eureka CA, helps
Logan Shaw, who ended his first float flight smiling.
Some sort of retrieval boat is required. Organized float-flys often
have sophisticated arrangements, but a canoe, a kayak such as the
one Charlie Hoisington (Redding CA) is using, or a two-man
inflatable will work as well.
Twin-rotor autogyro on floats, anyone? These models are
becoming extremely popular at indoor events. This one is built
from the GWS Slow Stick and equipped with GWS floats.
It is often said, “If it will fly on wheels, it will
fly on floats.” Richard Lucas (Fort Bragg
CA) learned that his rotating-wing (not
rotary wing) model flies either way.
E-flite’s Mini Ultra Stick is a terrific compact
electric aerobat, and it is just as good on
floats. You can throw it in your car’s trunk
and fly it almost anywhere there is water.
Some of the earliest full-scale airplanes were
sometimes put on floats. Balsa USA’s Taube
sports a set of tail-dragger floats, which take
some getting used to.
This is one of the safest recovery methods.
He doesn’t even have to lean over to pick
up the airplane. There is often as much
ingenuity in retrieval methods as there is
in the models themselves.
Scale seaplanes such as Great Planes’ Seawind can be a
handful on the water. Jim Feldmann made this pictureperfect
takeoff. He really enjoys this model.
The quickest way to start float-flying is to put floats on an old trainer you don’t
use much anymore. This Avistar flies as well on sheeted-foam floats as it did on
wheels. Keep the weight down with light floats and struts, and the model won’t
know they’re there.
42 MODEL AVIATION
Bruce Taylor and Nick Troehler share the duty of
bringing in a stalled Seamaster. Rule number one at a
float-fly: Don’t strafe the retrieval boat!
What Models Work Best?
Almost any airplane (or helicopter) will work on floats, but some
do better than others. Floats add a fair amount of weight to a model,
so you should start with a model that has a low wing loading, such as
a trainer or a light sport aircraft.
A low-wing airplane will work better on water than a high-wing
airplane will, simply because the wing is closer to the water and less
likely to be blown over in a crosswind taxi. Low-wingers are better
balanced for aerobatics too, with the floats below the wing and the
rest of the airplane above it.
High-wingers on floats are exceptionally stable in the air.
However, the extreme pendulum effect of the floats hanging down
under the fuselage makes turns and rolling maneuvers look strange.
Scale models tend to be harder to fly than sport models, and scale
floatplanes (such as the ubiquitous
Cub) are harder to fly than sport
floatplanes. The best-performing
and easiest-to-fly floatplane would
be something similar to a Sig Four-
Star kit or ARF, Goldberg Tiger kit
or ARF, or any of the Stick
variations. MA
—Jim Feldmann
• Set your airplane’s rudder for all the travel
you can get, and use exponential as needed to
calm it around center.
• Water rudders are optional. High-wing and
multiengine models usually need them; lowwing
models usually don’t.
• Rebalance the airplane after the floats (and
ventral fin, if used) are installed. If you need to
add balance weight, add it to the floats—not
the airplane.
Propellers: Wood propellers don’t mix with
water. The water that splashes into the
propeller will shred the wood before you even
get off the water. You can use any plastic
propellers, such as those from APC or Master
Airscrew.
The wind has a much greater effect on the
model when it’s taxiing on water than on land;
the water gives, where the ground stays put.
No matter which way the airplane is pointed, it
will move downwind unless you drive it some
other way. If there is a current in the water,
that will also have an effect. Taxiing on water
is similar to taxiing a tail-dragger on land.
When taxiing in a straight line, hold full
up-elevator and use approximately one-third
throttle to keep the back of the floats down in
the water and give the air rudder plenty of
steering authority.
If the floats come up on the step, slow
down until they settle back into the water. A
fast taxi on the step is a good technique for
windy conditions, but it requires practice. You
better take it slow.
When turning, slow to a walking pace,
release the elevator, and steer with the air
rudder, using bursts of throttle to kick the tail
around as needed. Hold full aileron toward the
wind to keep the upwind wing down.
Taking off From Water: Doing this is similar
to taking off from land with a tail-dragger. It is
actually easier to take off from water because
you can normally take off directly into the
wind, and you will need much less right
rudder to counteract torque.
Taxi out to the takeoff area, throttle back,
and let the airplane weather-vane into the
wind; you should still be holding full upelevator.
Advance the throttle smoothly while
releasing the elevator. The airplane will rise up
on top of the water and run along like a fast
boat.
When the airplane has reached flying
speed, add slight up-elevator and the airplane
will break the surface tension of the water and
take off. That “break” may cause a radical
pitch-up attitude, which you should quickly
correct to prevent a stall. Remember that
flying speed will need to be a bit faster
because of the floats’ weight.
Hold slight up-elevator until your model is
well out of ground effect. If you have a water
rudder, do not move the rudder stick during
the high-speed takeoff run. Water rudders are
incredibly effective at high speeds and can
easily cause a water loop.
Flying a Floatplane: Your model will fly
almost the same on floats as it did on wheels.
You will need a little up-trim on the elevator
to counteract the floats’ drag. The airplane is
heavier and draggier than it was on wheels, so
it will climb slower and come down faster.
Floats have a tendency to tame aircraft, so
you’ll find that aerobatics will be bigger and
smoother. The floats will create added lift and
actually make inverted and knife-edge
maneuvers easier. Be cautious when
performing spins; the added momentum of the
floats can make it more difficult to recover.
Landing a Floatplane on Water: Again, the
floatplane acts like a tail-dragger on land. All
water landings should be flared three-point
touchdowns. There is a great deal of drag
when the floats touch the water, and if you fly
the model onto the water in a wheel-landing
(tail high) attitude, there is a good chance that
it will flip upside down.
Following are some landing rules.
• Land directly into the wind, and try to land
downwind of your retrieval point.
• Keep your floatplane’s speed slightly faster
than you would for a ground landing.
• Fly down to a couple feet above the water
and then cut the throttle and flare by holding
altitude with the elevator. As the speed bleeds
off, the airplane will slowly settle onto the
water. Once on the water, the airplane will
slow more quickly than it does on land.
• Taxi back to shore in as straight a line as
possible to avoid taxiing crosswind. Keep that
upwind wing down by holding the aileron up.
• Try to wipe that silly grin off your face!
Everything is going to get wet if you flip
your model over or crash it. Fresh water will
not permanently damage your engine or radio
if you dry them out as soon as you get them
out of the water. Salt water, on the other hand,
will quickly destroy them.
If the worst happens, start the engine and
run it until it is good and hot, to evaporate any
water that is inside. Run it for at least five
minutes for a two-stroke and a whole tank of
fuel for a four-stroke. Then load up the engine
with a liberal dose of after-run oil.
Take the receiver, battery, switch, and any
servos that were underwater out of the
airplane and open them up. Blow out as much
water as you can, and then let them dry in the
sun.
Damage to electronics occurs when
mineral deposits form on metals. Lake water
is loaded with minerals. Using a soft plastic
brush and distilled water will help clean
electronics that might be dirty.
Both the engine and the radio should be
fine after the water has completely
evaporated. The model will typically survive
and can be repaired once the parts are dry.
Tips for Success: There are several things
you should pay attention to if you want your
first float-flying experience to be successful.
Avoid flying an underpowered model; you
will need a little more power for takeoffs from
water. This is not a problem for the average
sport model, but a low-powered trainer or
scale airplane might need more. Switching to
a larger-diameter, lower-pitch propeller may
help.
The rules of thumb regarding an improper
float setup are flexible, but there are limits.
Floats that are mounted too close together, not
parallel to each other or to the fuselage, or
with the step too far forward or too far back
will be problematic. The step should be under
or ahead of the CG.
Too much or not enough positive incidence
in the wing will make it difficult or impossible
for the model to take off from water.
Not having enough area in the fin and
rudder to offset the float area added in front of
the CG, which frequently happens with the J-3
Cub, will make the airplane unstable at takeoff
or during slow flight. If you don’t want to do
the math, add a subfin just to be safe.
If the airspeed on takeoff or landing is too
slow, the model will stall. Remember that you
need more speed to lift the extra weight of the
floats. If your airplane takes off too soon or
slows too much on the landing approach, it
will stall and everything will get wet. The full
throttle-and-full up method of takeoff seldom
works on the water.
Examine the float design carefully. The
shape and finish of the bottom of the floats is
critical. It is probably best to buy your first set
of floats. If you want to build them from
scratch, wait until after you know more about
them.
Flying from water is another great way to
enjoy model aircraft, and it is so much fun that
it is almost addictive. Try it; I bet you’ll like
it! MA
Jim Feldmann
[email protected]
Sources:
Ace Hobby Distributors
(949) 900-3300
www.acehobby.com
APC Propellers
(530) 661-0399
www.apcprop.com
Carl Goldberg Products
(217) 398-8970
www.carlgoldbergmodels.com
Great Planes Model Distributors
(217) 398-8970
www.greatplanes.com
Hangar 9
(800) 338-4639
www.hangar-9.com
Hobby Lobby International
(866) 933-5972
www.hobby-lobby.com
Master Airscrew
www.masterairscrew.com
Plane Fun Floats
www.geocities.com/planefunfloats
Sea Commander
(604) 485-2976
www.seacommander.com
Sig Manufacturing
(641) 623-5154
www.sigmfg.com
July 2008 43